Abstract:

Taking actual domestic wastewater (C/N = 3.5) as influent substrate and carbon fiber as biological carrier (filling rate of 35%), the simultaneous nitrification and denitrification via nitrite was achieved in a sequencing batch biofilm reactor (SBBR) using limited DO concentration and intermittent aeration respectively at normal temperature of (20±2.0)℃. The ammonia oxidizing bacteria (AOB) became the dominant species in the SBBR in 120 d. The “feast-famine” characteristics of AOB led to the rapid accumulation of nitrite under intermittent aeration conditions. Most of COD was taken up and converted to polyhydroxyalkanoate (PHA), which was used as internal carbon sources for the following denitrification process. Under the conditions of low oxygen (DO=0.5 mg/L) and intermittent aeration, the removal efficiency of \mathrm{N} {\mathrm{H}}_4^{+} -N in both reactors was more than 95%. The yield of N₂O was 4.38% and 3.65%, the SND efficiency was 77.9% and 87.1%, respectively. The effluent was mainly \mathrm{N} {\mathrm{O}}_2^{-} . Both the lower DO concentration and intermittent aeration could reduce the degradation rate of COD, provide the external carbon source needed for denitrification, and reduce the amount of N₂O emissions. The aerobic denitrification process of AOB and denitrification process of \mathrm{N} {\mathrm{O}}_x^{-} -N using internal PHA as carbon source can promote the emissions of N₂O. The anoxic/aerobic environment under intermittent aeration conditions reduced the substrate of aerobic denitrification substrate and is beneficial to the reduction of N₂O emission.

Key words: simultaneous nitrification and denitrification via nitrite, DO, intermittent aeration, N₂O, PHA

摘要：

以实际生活污水为处理对象，利用序批式生物膜反应器（sequencing batch biofilm reactor，SBBR），碳纤维为填料（填充率35%），在(20±2.0)℃条件下，分别通过低氧和间歇曝气两种运行方式，成功实现了亚硝酸型同步生物脱氮（simultaneous nitrification and denitrification, SND）过程。120 d后，氨氧化菌（ammonia oxidizing bacteria, AOB）成为硝化系统中优势菌种。AOB具有的“饱食饥饿”特性保证间歇曝气下能快速实现亚硝积累。生物膜能够吸附大量有机物并以聚β–羟基烷酸酯(poly-β-hydroxyalkanoate, PHA)的形式储存在微生物体内，用作后续同步反硝化过程所需碳源。低氧（DO=0.5 mg/L）和间歇曝气条件下，SBBR反应器氨氮去除率均达95%以上，同步脱氮效率分别为77.9%和87.1%，出水以 \mathrm{N} {\mathrm{O}}_2^{-} -N为主，N₂O产率分别为4.38%和3.65%。低DO和间歇曝气均能降低COD降解速率，为同步反硝化过程节省外碳源作为电子供体，降低N₂O释放量。低氧条件下，AOB的好氧反硝化过程和以PHA作为内碳源的异养菌反硝化过程，都会导致N₂O释放增加。间歇曝气条件下交替存在的缺氧环境降低了好氧反硝化底物，有利于减少N₂O释放量。

关键词: 亚硝酸型同步硝化反硝化, 溶解氧, 间歇曝气, N₂O, PHA